A cutterhead of this type is known from published German patent application DE-OS 28 55 990. In this cutterhead, the flexible cutting filament, for example a plastic filament, is wound on the spool. The plastic filament is consumed by wear during operation and is thereby shortened. The plastic filament is readjusted by a predetermined length via a coupling part corresponding to the spool and the housing and this coupling part is in the form of a pivotally journalled lever biased by centrifugal force. The coupling part is configured as a two-arm lever in the manner of a rocker having a pivot axis which lies outside of the center of gravity. The bifurcated coupling part has two prong-like cams with which the coupling part engages in catch recesses in a first and in a second catch position. The catch recesses are configured by cam-like catches which are provided inside on the take-up spool for the cutting filament.
In this known embodiment, the coupling member includes the two prong-like catches and is provided for a bearing pin in the outer region of the cutterhead housing with the bearing pin being provided on the housing. In this way, a relatively unwieldy or large configuration for the cutterhead is provided. Furthermore, the coupling member is pivotally mounted outwardly and together with its journalling support influences in a very unfavorable manner the unbalancing conditions of the cutterhead running at very high rotational speed.
It is characteristic for the species of the above-mentioned known cutterhead that the cutting filament wound on the spool is readjusted without intervention of the operator, that is without manipulation by the operator. The readjustment takes place automatically in dependence on the magnitude of the centrifugal force and in a stepwise manner with the wear of the cutting filament; however, the cutting filament is not guided over the pivotable coupling member. The coupling member causes the spool to rotate through a rotational segmental distance relative to the housing in dependence on centrifugal force thereby releasing a pregiven length of the cutting filament. The cutting filament is however not guided via the pivotable coupling member. In this way, the coupling member is not itself directly biased by the cutting filament and is not directly influenced by the filament, for example, by friction. The switching cams in the known cutterhead lie within the spool. These switching cams like the prong-like cams must have very tight tolerances in order to effect a precise switching which besides being relatively expensive in manufacture is also disadvantageous because of a high surface pressure. The prong-like cams operate with the switching cams and are provided on the pivotable coupling member.